Regionally Owned Enterprises (BUMD) play a very important role in realizing the prosperity and prosperity of an area by contributing income or contributing to the Regional Original Revenue (PAD) cash. After the Constitutional Court Decision Number: 85 / PUU-XI / 2013, certainly had a very big impact on the water supply system, the purpose of the research was to find out the regulation and management of Water Resources in the Municipal Water Company (PDAM) of the City of Yogyakarta, legal research methods normative, the result of this research is that the management concept must still refer to Article 33 paragraph 3 of the 1945 Constitution, with priority by BUMN or BUMD. As well as the Yogyakarta City Tirtamarta PDAM, in running its business, it is in accordance with Regional Regulation No. 14 of 2012 concerning the Yogyakarta City Tirtamarta Water Supply Company and PP No. 54 of 2017 concerning Regional-Owned Enterprises.